| 摘要 |
PURPOSE:To manufacture the titled polycrystalline magnet having high performance for peripheral magnetization by subjecting a polycrystalline Mn-Al-C alloy magnet having uniaxial anisotropy to warm free compressive working in the anisotropic direction, especially compressive working divided into a plurality of times through a state with plastic working stopped. CONSTITUTION:A known Mn-Al-C magnet alloy such as an alloy consisting of 68-73wt% Mn, (1/10Mn-6.6)-(1/3Mn-22.2)%C and the balance Al is prepared, and the structure of the alloy is converted into uniaxial homogeneous fine [001] fibrous structure by a known method such as warm extrusion at the temp. range of 530-830 deg.C. The alloy is then subjected to compressive working divided into a plurality of times through a state with plastic working stopped in the axial direction. At this time, after applying a positive plastic macro-strain in one specified direction, a negative plastic strain is applied in the same direction in a plurality of times so that the compression up to >=-0.1 logarithmic strain is necessarily made free. As a result, the residual flux density can be increased by about 0.2kg as compared to continuous compressive working equal to this working method in the total quantity of compressive strains. |
